The Gravity Recovery and Climate Experiment (GRACE) satellite has provided a new means to study the deep earth structure and to keep track of mass changes of earth surface.In this paper,applications of GRACE data in the scope of hydrology are summarized on the basis of extensive reviews of relevant literature.This paper starts with a brief introduction of the common available scientific GRACE data sets.Applications in estimating oceanic and terrestrial water storage,as well as those of polar and alpine glaciers are then reviewed,and the approaches to validate the GRACE estimates are followed.Technical issues encountered in hydrological applications and their possible solutions are examined in details.We concluded that it is critically important and valuable to employ the GRACE satellite data to monitor global or regional scale water balance to meet the challenges of global/regional hydrology monitoring and research.
Based on the protensive GIMMS NDVI data set and meteorological data during 1982~2009 in the Heihe River Basin,a novel multiple time\|scale analysis method,Empirical Mode Decomposition (EMD),is used to diagnose the periodicities of NDVI,air temperature and precipitation data.At the same time,the relationship among these three elements was performed.The results indicate that SINDVI,temperature and precipitation have the similar 3 and 10 year quasiperiodics in the upper reaches of the Heihe River Basin.SINDVI and temperature have the similar 3、10 year quasiperiodics,SINDVI and precipitation have the similar 3、6、8 and 15 year quasiperiodics in the middle reaches of the Heihe River Basin.In the meantime,in the lower reaches of the Heihe River,SINDVI and temperature have the similar 3 and 10 year quasiperiodics,SINDVI and precipitation have the similar 3 and 6 year quasiperiodics.It is indicated that the temperature and precipitation are both the factor affecting the vegetation in the Heihe River Basin.In addition,the EMD method can be effectively used to analyze the relationship between time\|series data with the meteorological data.
The objective of this paper is to analyze land use and land cover dynamic in the county regions,and to give some constructive suggestions and improve the local quality of ecological environment.Based on the three dates remotely sensed data in 1987,1999 and 2007,this paper analyzed the characteristics of land use change in the Huangzhong County during the period of 1987 and 2007.Transition matrix of land use types,land use dynamic degree and land use intensity index was calculated in Huangzhong County,and land use intensity index was compared with that of other two typical regions in china.The results showed as follow:① The area of forest land was increased from 1987 to 2007,and the cultivated land area was decreased;② The cultivated land area in Huangzhong County had an obvious fluctuation from 1987 to 2007;③ The annual change rate in the first period (1987~1999) was significantly less than that in the second period (1999~2007);④ The average land use integrated index in Huangzhong County was 252.35,which was more than those Counties' along Qinghai Lake,and less than those Counties located in the middle of Yangtze river.
The uncertainty and sensitivity analysis of surface turbulent fluxes to model parameters (leaf area index,surface albedo and vegetation coverage fraction) is studied,which uses meteorological forcing data from December 22,2007 to December 31,2009 at the Arou observation station in Heihe river basin.The result shows that surface turbulent fluxes are all quite sensitive to leaf area index,surface albedo and vegetation coverage fraction.As for leaf area index,the sensible and latent heat fluxes from canopy are more sensitive to leaf area index than other turbulent fluxes,the sensitivity coefficients are all above 0.7.As for surface albedo,sensible heat fluxes are more sensitive to surface albedo in comparison with latent heat fluxes.The sensitivity coefficients of ground,canopy,and total sensible heat fluxes to surface albedo are about -0.96,-0.97 and -0.66,respectively.The sensitivity coefficients of ground and total latent heat fluxes to surface albedo are very low and the value is only about 0.1.In terms of vegetation coverage fraction,latent heat flux from canopy is the most sensitive to vegetation coverage fraction in comparison with other turbulent fluxes,and the sensitivity coefficient ranges from 0.92 to 0.96,while the sensitivity coefficient of sensible heat flux from ground to vegetation coverage fraction is very low and the value is only about 0.18.
According to Comprehensive Sequential Classification System(CSCS),potential grassland classification map was made and potential grassland NPP was statistical analyzed in Gannan by using of global climate interpolation data sets from 1950 to 2000.The result shows that grassland of Gannan can be classified into 7 classes,including Frigid perhumid rain tundra\|alpine meadow class,Cold temperate-humid montane meadow class,Cool temperate perhumid mixed coniferous broad leaved forest class,Cool temperate\|humid forest steppe-deciduous broad leaved forest class,Warm temperate-humid deciduous broad leaved forest class,Warm temperate-subhumid forest steppe class and Warm temperate-semiarid warm temperate typical steppe class.The annual average NPP increased gradually from northwest to southeast in Gannan.And total quantity of NPP was up to 23.08TgC,in which Frigid perhumid rain tundra\|alpine meadow class and Cold temperate-humid montane meadow class as main body.Elevation has a significant effect on annual average NPP which decreased as the elevation increased.However,the influences of slope and aspect on annual average of NPP was not significant.
The built up boundaries and areas of Zhangye City in Ganzhou region in 1959,1968,1977,1986,1997 and 2009 are extracted from keyhole,MSS,TM images,topographic maps and other auxiliary data.The analysis on the spatial expansion of the land use over the past 50 years is based on the spatial center of gravity transfer model,urban expansion intensity index,urban expansion rate index,compactness index,area change,expansion index of urban built\|up area etc.Studies show that the area of the built\|up region expanded 5.71 times during the 50 years.The expansion was in the low growth stage from 1959 to 1986 while it was a rapid growth stage from 1986 to 2009.The built\|up region is expanded only 258.42 hm2 from 1959 to 1986 due to the influence of natural disasters and the “cultural revolution”.However,its built\|up region area has increased 1 995.11 hm2 which is 7.73 times as the change in early 27 years from 1986 to 2009 due to the overall progress of the reform and opening-up,the implement of the Western Development Strategy.The offset of the city barycenter is little from 1959 to 1977.Although the expansion area of the city is little between 1977 and 1986,the main expansion direction of the city is west and northwest which causes the city barycenter shifting to northwest quite a large.The barycenter of the city began to shift to the east and northeast with a more offset and the most can reach to 629.79 m from 1977 to 2009 due to the expansion of the city is mainly towards the east and northeast.The compactness of the city declined sharply between 1959 and 1968,however,it is opposite between 1997 and 2009.The change of the compactness of the city became stable from 1968 and 1997.The city land use scale expansion is insufficient from 1959 to 1986 due to the expansion index of urban built\|up area is less than 1.12,but it is opposite between 1986 and 2009.
The near-surface soil moisture data retrieved from passive microwave sensors has the coarse resolution,while the study in a river basin need soil moisture data in high spatial resolution.LST\|NDVI space is generated by MODIS Land Surface Temperature Products(MOD11A1) and MODIS Surface Reflectance Products(MOD09GA) and Temperature Vegetation Dryness Index is calculated based on that.The index indicate spatial pattern of soil moisture and which is linear regressions with soil moisture.We calculate the linear regression coefficients between TVDI and near\|surface soil moisture at the passive microwave scale,and then calculate soil moisture data at MODIS scale.The root mean square error between 0.01 resolution and ground\|measured soil moisture collected during the National Airborne Field Experiment 2006 is 6.1%.
Electronic map plays an important role in county Geospatial Information platforms.Traditional electronic maps are stored on server computer in file sets,which leads to the hard release and sharing process of maps.This paper presents a method of electronic map release and sharing in County Geospatial Information Platform.In the method,electronic maps are distributed in different server computers at different platform nodes;meanwhile,tile\|pyramid is used to realize web release of these electronic maps,which makes the map scanning fast and fluent.In conclusion,map tiles,web services as well as geographic information service techniques offer a new path in electronic map release,sharing of County Geospatial Information Platform.
With its macroeconomic and real\|time,Remote Sencing(RS) can be used to study the spatial pattern and time trend of carbon stock of terrestrial ecosystems.RS technology plays an important role in estimating the carbon sink function of terrestrial ecosystems.For carbon storage in terrestrial ecosystems in China,many scholars have made great results.However,most studies just concerned about a certain type of ecological system,and research on rapid economic develoment regions is even less.According to the methods in measuring greenhouse proposed by IPCC-LULUCF,using of data from Remote Sensing and literature,this paper analyses the carbon sink function of terrestrial ecosystems of Wuxi City from 1991 to 2005.As a result,the land use of Wuxi City has a great changes form 1991 to 2005,especially the conversion between different land use types is obvious.Because of the land use change,the carbon storage reduces 145.18×104 t totally,so the terrestrial ecosystems is a carbon sink.Particularly:the carbon storage of ground,underground and soil decreased by 145.91×104 t,59.87×104 t and 251.40×104 t.As far as the carbon sequestration potential,the forest is largest for 190.71 t/hm2,followed by 121.186 t/hm2 for grassland,the smallest is 92.6 t/hm2 for agricultural land.The reduction of forest area results a number of carbon released.
The field measurement of coastline has much difficulty and a long measurement cycle,so it is not suitable for normal investigation.In view of this,we studied the method of coastline extraction using satellite remote sensing image with high resolution and DEM.Taking SPOT 5 image as an example,we gave the establishment method of interpreting marks and extraction principle for rocky,gravelly,sandy and artificial coastline.Especially for the sandy area,the image should be stretched before coastline extraction.With regard to the shortages of coastline extraction by remote sensing only,we put forward several ways that combined with fine DEM data,analyzed the reliability of elevation obtained from sandy coastline based on interpreting marks,and then gave the instances of extracting rocky coastline.Finally,comparied with the field measurement result,the positioning accuracy of the extracted coastline is better than 5 m,which can meet the requirement of mapping accuracy for 10 000 scale.
The coastal protective forest in Quanzhou bay was extracted and the change detection technique was employed to reveal the change of coastal protective forest in Quanzhou bay from 1987 to 2008,and the scientific decision making was provided for forest construction and protection.This paper employs the decision tree classification of remote sensing technology to extract the coastal protective forest.The results shows that a total of 537.23 hm2 coastal protective forests have been increased from 1987 to 2008,the main protective forests are Broadleaved forest,account for 70%~80%.On the whole,the Broadleaved and coniferous forest both increases continuously,and the mangrove decreases in the first 9 years and increases in the later 21 years; but protective forests decreases in local areas,especially in Fengze district,because its spatial expansion occupied large area of protective forests.Though the protective forests in Quanzhou bay increase to some extent,their spatial distribution are incompletely reasonable.Therefore the protective forests in Quanzhou bay can not protect Quanzhou coastal developed region effectively.
It is an important channel for remote sensing users to apply for satellite programming data by using the application system of satellite observation planning.To improve the efficiency and quality of the application,an online analysis application system is proposed through analyzing the shortcomings of the current systems.Then the key technologies of the system are described in detail and a prototype system is developed.At last the systems performance has be tested and evaluation is implemented.The result of evaluation shows that the system,with high running efficiency,is able to make on-line real\|time analysis of multi\|satellite observation application and provides a fairly good support to apply for satellite programming data.
The object of the digital precipitation forecast system of Three Gorges reservoir is provide an effective tools to assist forecaster in two parts,one part is managing,simulating forecast and evaluating the vast precipitation data from different sources,another part is calculating and analyzing regional precipitation by different schemes of precipitation forecast zoning.The number of precipitation forecast zones can even reach 50,which is very difficult to calculate by manual.Based on SuperMap GIS component,the research designs and implements the digital precipitation forecast system of Three Gorges reservoir,which includes managing different schemes of precipitation forecasting zones,the interactive forecasting with forecasts with automatic or manual method,the auto\|saving into database of forecasting results,and the displaying of the forecasting results on Web by picture or animate pictures.The structure,functions,distribution and precipitation forecasting flow of the digital precipitation forecast system of Three Gorges reservoir were introduced in this paper,and the system has successfully applied in the service of precipitation forecasting of Three Gorges Cascade Dispatching Center.
Synthetic Aperture Radar leads on the Remote sensing technology due to its excellent advantage such as independence of sunlight can work in all weather conditions and all day and all night,not easily affected by cloud and rain.Synthetic Aperture Radar data Feature-Tracking (SRFT) procedures can overcome the shortcomings of Interferometric Synthetic Aperture Radar (InSAR) due to decorrelation to obtain glacier surface velocities robustly.In order to discuss the suitability of the Feature-tracking procedures, To find the suitability of different SAR data sets to derive glacier surface velocity,SRFT of ALOS PALSAR Data and ENVISat ASAR data were employed and compared to obtain the Koxkar Baxi Glacier surface velocities.Data with different time intervals (temporal baseline) were used to calculate the glacier surface velocity.Which were validated by the in situ measurements.SRFT is a robust technology to derive mountain glaciers surface velocity while SAR interferometry may fail.The uncertainties were analyzed in the same time.We find that the velocities obtained in debris-covered area were well agreement with the in situ measurements.There exist much more uncertainties in the exposed ice regions where there are no apparent characteristics observed.And for long baseline datasets the weather conditions when SAR data acquired in the glacier region should be considered or lead to the occurrence of more errors.Its clear that L-band ALOS PALSAR data are more suitable for Feature-Tracking than ENVISat ASAR data in estimating mountain glaciers surface velocities due to the wavelength or polarization difference.
Based on the backscattering data of CALIOP(Cloud-Aerosol LiDAR with Orthogonal Polarization) in March and April in 2010,this paper give a new method of data processing using IDL which produce the spatial distribution image of backscatter signals and other parameters .Based on this,it gives the further study of the dust distribution of Beijing in spring.The study of the attenuated backscatter and depolarization ratio as well as the height distribution of the dust storm in the visible light and infrared band shows that:the spatial distribution image of backscatter signals and other parameters when laser transmit in the atmosphere can depict the components of atmosphere and their distribution condition such as that of aerosol,dust storms and clouds.With the tracking figure provided by NILU,this paper concludes the origin of the dust storm and provides an important basis for the impact of dust storm to climate.
The distribution of hydrometeor phase is the basis factor for determining the water content of cloud and precipitation.By using the WACR data from ARM Mobile Facility (AMF),Shouxian,China,the hydrometeor phase vertical distribution is retrieved with fuzzy logic algorithm.First,the membership functions of fuzzy logic method for reflectivity,Doppler mean velocity,spectral width and the temperature are established by the threshold of Shupe,and the asymmetric trapezoidal membership function is chosen as the form of the membership functions,the depolarization ratio membership function is established by scattering characteristics and geometric shape of different kinds of hydrometeor.Then,the vertical phase distribution of hydrometeor is retrieved by these established membership function with Shouxian WACR data.The main conclusions are got as follows:the more accurate results can be acquired with MPL data for thin cloud layer,but in deep cloud case the polarization information of WACR is helpful to improve the precision of retrieval.We can get the distribution of hydrometeor phase using the data of 3 mm radar with fuzzy logic algorithm,the results are reasonable,but the choose of T-function coefficient need further research.
Frequent geohazard in China have caused heavy casualties and economic losses.“5·12” earthquake induced a large number of geohazard such as landslides,collapse,debris flow and barrier lake etc.causing significant loss of life and property.Practice shows that the use of remote sensing technology can be a wide range of geohazard survey and monitoring,but also a marked improvement in response speed.But currently there are more types of sensors,so how the laws are found in mass data,how to collaborative process data,and how to make up for the deficiency on information extraction capabilities is a serious problem.This paper,based on the analysis of the commonly used image fusion method and combined with the task of investigating the geohazard and specific circumstances of the study area,regards full color multi-spectral SPOT and TM images as the data source and carries out the data fusion algorithm and image quality evaluation,so as to obtain good results,which not only retains the multi-spectral images of spectral information,but also increases space of the amount of information fusion images to make up for the shortage of the amount of information of single data and to improve pregnant disaster factor and hazard\|affected body extraction accuracy.So those have played a role in technology support in the geological hazard and risk assessment of geohazard,and their research on the geohazard\|prone areas of disaster prevention and mitigation and disaster sensing mechanism is provide with reference.
IHS(Intensity-Hue-Saturation) color space is more consistent with human visual system than RGB color space,so IHS transform has been used widely in image fusion.The most significant problem of the traditional IHS transform fusion method is that the fused image usually has a notable deviation in visual appearance and in spectral values from the original image.In this paper,we propose a new IHS transform fusion method based on Structural Similarity (SSIM).First,the multispectral image was transform from RGB color space to IHS color space,then we calculate the SSIM matrix between the intensity component of the multispectral image and the panchromatic image.The new intensity component is determined based on the SSIM.Experimental results indicate that this method is effective in preserving spectral and spatial information.
Imaging geometric model is the foundation of geometric analysis of the remote sensing images and spatial information collecting.For different geometric location models,rigorous geometric models have the advantages of high\|accuracy and high reliability,so it has great significance for the study of rigorous geometric models.In this paper,rigorous geometric models for images from high resolution remote sensing satellites in recent years are presented.Three typical rigorous geometric models,including the rigorous model implemented in the software SISAR,geometric models based on unit quaternion and geometric models based on dual quaternion,were introduced in special detail.Dual quaternion can describe the position and attitude of space image,so the study of geometric models based on dual quaternion has great development prospects.
To meet demand of quantitative application for HJ-1 satellite data,a vicarious calibration experiment for CCD cameras onboard HJ-1A and HJ-1B satellites was proposed in the middle of October 2008.The reflectance-based method was used.The radiometric response change of each CCD camera was ascertained and error analysis of the calibration coefficients was developed.Meantime,regarding apparent radiances obtained from CCD data of the synchro measurements at Dunhuang test site and Gongger test site as the standard values,which were not at the same day as the calibration experiment,validation research of the calibration coefficients was performed.It showed that the apparent radiances obtained by calibration coefficients were fairly consistent with the standard values and the errors were all less than 3%.It was proved that the calibration result has high accuracy.And then an average value of calibration coefficients from both synchro data was determined as the last result.The result laid the good foundation for quantitative application of CCD cameras.
Drought monitoring and other practical applications all need to obtain comprehensive spatial distribution of LST,but cloud cover is a major barrier of this process.We attempt to study the method of estimating vegetation surface temperature of cloudy areas in the remote sensing images by the relationship between changes of LST and ground vegetation.Because of the vegetation transpiration,the density of vegetation has a great effect on changes of spatial distribution of LST.This effect not only exists in cloudless areas,but also can be applied to the cloudy areas.Therefore,we first analyzed the relationship between LST and NDVI in cloudless areas which were nearby cloudy areas and established the equation;Then we used the feature that NDVI was stable within a short time to acquire NDVI value of cloudy areas.At last,we estimated the LST of cloudy areas according to the relationship between the NDVI and LST.We applied this method to Landsat ETM+ images of Liaocheng city in Shandong province.The results show that,when the cloudy area is within or equal to 2 000 pixels(about 1.72 km2),the mean absolute error(MAE) of LST in cloudy area which estimated through NDVI is little than 0.7 ℃,the RMS is<1.2 ℃.In order to verify its practicality,we also applied the method to TM images of Bengbu in Anhui province,when cloudy area is within 300 pixels,the MAE is less than 0.1 ℃.Hence,it can be argued that when the range of cloudy area is not very large,using NDVI to estimate the LST of cloudy area has certain feasibility.
The research of spatial data specification and description mechanism is very important for spatial information sharing and services collaboration,especially in grid environment.Most of the studies focus on the content composition and implementation of specific standards,but not aims the procedure in data integration.This paper based on the data service architecture in grid platform,and analysis the relevant data specification and standards.We study the resource description method and metadata strategy,and summarize a standards series of spatial resources description for data grid service.The paper gives the application in Spatial Information Grid platform for case study,and discusses the result in detail.
